Originally posted by PederBass And, doesn't Mark Levinson use it in their dac's?

They only use it in ML37 player. Their other DACs use discreet buffer.

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Originally posted by PederBass Just wonder what ur opinions are on Buf634T? I will use it as a output buffer in a closed loop circuit (in a headphone amp).

It doesn't seems to be popular on some headphone - forums , therefore I felt that I must ask u people here...and yes I know that Carlos seems happy with it, but how about the rest of u?

I at least am very pleased with BUF634 and the "F" model (SMD, TO220). Together with OPA627, AD8610 and OPA134 I think it's an excellent combination. I have also tested the buffer in "medium speed" and "high speed" without any big differences. Medium speed is to have 3.9 kohms from BW pin to V-.

You can try to get samples, cost you nothing but you can also build a diamond buffer quite easily with very good results. Check my designs for inspiration. All of these are "high speed, low distortion versions" with cascodes but you can make it. QRV-03 is made of ordinary parts and the other two are made of SMD parts.

I had compared this type with similar discrete one ( something as Jung's diamond buffer ). Both was connected to feedback loop of opamp ( OPA 134, OPA 627 ), both was set up to the same BW ( 1 MHz ), both had the same load impedance ( 50 Ohm ). I bias of 634 was 15 mA, discrete was cca 25 mA. In discrete was used normal cheap transistors ( BC 546 / BC 556, BD 139 / BD 140 ), not any " exotic " high speed types. And results ? Discrete win " two horse lenhg " in all aspects, mainly in much more firm bass. Interesting of this solution is also price - it is ten times lower .

I did build a buffer with the BUF 634 and compared it with the Misical Fidality X10D. I did used battery powersupply from a drilling machine and add some capacitors. The 634 did easy win this from the X10D.